Game Difficulties - OK to change "deep" control-variables?

Hello fellow GameDevs!

This is my very first post here, and i'm sorry, if i posted something wrong.

Prolog: 
I made a plattformer with only jumping/climbing challenges and without any evil NPCs that could kill the Player. Just jumping around.
My 2 younger Brothers tried it yesterday and i observed, that this game is a bit harder for new Players, than i thought. Now i'm thinking about setting different difficulties (easy, medium, hard) or dynamic difficulty-change (change difficulty after 5-10deaths, changing back after level completed).

Question:
What do you think about slightly changing deep control variables …